Conventionally, a cutting insert (hereinafter sometimes abbreviated to “insert”) is known in which a coating layer including a single layer or a plurality of layers is formed on the surface of a base body made of a hard metal alloy, such as cemented carbide alloy or cermet, or of ceramic and the like, using a thin film forming method, such as a CVD method.
When forming the coating layer on the insert using the CVD method, several thousands of the inserts are set inside a film forming device, and film formation can be performed simultaneously, thus enabling efficient film formation. As a method for setting the inserts, conventionally, a general method involves providing opening portions for placing each of the inserts on a support substrate on which the inserts are set, placing the inserts in a state of being diagonally inserted into the opening portions, and performing film formation. In this method, the coating layer is not formed on a contact portion between the support substrate and the insert, and remains as contact traces. Since the contact traces are formed on an edge portion of the insert, when these contact traces are present on a cutting edge, wear resistance deteriorates partially at the contact traces, and becomes a cause of property variations.
Here, for example, in Patent Document 1, a method is proposed in which a peg, which is made from a ceramic material, reinforced graphite, or a molybdenum cemented carbide alloy and which is provided with a leg and a shoulder, is fitted into a support substrate, the peg is inserted into a through hole for inserting a screw of an insert, and a wall surface of an end portion of a through hole in the insert is caused to be in contact with the shoulder of the peg and is fixed.